The use of torque limiting clutches of various types to absorb shock loads in equipment is commonly known. Presently, friction type torque limiters are commonly used to couple electric motors and gear reducers that drive large chain conveyors, called armored face conveyors, to protect the drive system and the chain against the shock load generated by the motor inertia when the conveyor is jammed. The torque required to start an armored faced conveyor is generally more than twice the torque required to run the system at operating speed. The shock load generated by the motor inertia is at a maximum at operating speed and a minimum at zero speed. However, current torque limiters provide the same torque at all speeds and must be sized for maximum torque to start the conveyor. A torque limiter that could automatically reduce its torque setting as speed increases would provide the full torque necessary at low speed to start the conveyor, where motor inertia torque is minimal, and would provide a lower slip torque at operating speeds so as to improve the shock load protection during normal operation.
Conversely, there are applications envisioned where an increase in torque may be desired at operating speed, with a lower torque being desired at start-up.